Dynamic Dependency Analysis of Ordinary Programs 1

A quantitative analysis of program execution is essential to the computer architecture design process. With the current trend in architecture of enhancing the performance of uniprocessors by exploiting ne-grain parallelism, rst-order metrics of program execution, such as operation frequencies, are not su cient; characterizing the exact nature of dependencies between operations is essential. This paper presents a methodology for constructing the dynamic execution graph that characterizes the execution of an ordinary program (an application program written in an imperative language such as C or FORTRAN) from a serial execution trace of the program. It then uses the methodology to study parallelism in the SPEC benchmarks. We see that the parallelism can be bursty in nature (periods of lots of parallelism followed by periods of little parallelism), but the average parallelism is quite high, ranging from 13 to 23,302 operations per cycle. Exposing this parallelism requires renaming of both registers and memory, though renaming registers alone exposes much of this parallelism. We also see that fairly large windows of dynamic instructions would be required to expose this parallelism from a sequential instruction stream.